4-7 cam/plug firing order swap?

Discussion in 'TA Performance' started by melswildcat, Nov 17, 2014.

  1. melswildcat

    melswildcat Active Member

    Hi TA,
    Whats the theory behind the 4-7 cam/plug firing order swap.
    Saw the option in your catalog.
    Does the engine run smoother or is this a race trick?
  2. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    It's supposed to have better crankshaft harmonics and easier on main bearings. Every test I've seen as far as horsepower differences, it was within the noise.

    Modern engines, like the LS, have all gone to the 4-7 swap firing order. I think Ford had been using that firing order for decades when you decode their cylinder numbering order against their firing order.

    The roller cam in my Skylark has the 4-7 swap.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Mine also.
  4. B-rock

    B-rock Well-Known Member

    To bring back an old thread with the same Question. I read that the 4/7 swap was no longer that big of an issue?? Is that true? or is this still a thing to do?? Maybe a question for the street/strop category here??
  5. TABuickMike

    TABuickMike Michael Tomaszewski Jr

    The 4-7 swap thing was sort of a fad from the beginning. Everyone demanded that Buicks have 4-7 swap cams because everyone else was doing it, but we never sold very many.
    sriley531 and B-rock like this.
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    My engine has the 4-7 swap. Couldn't tell you if it is worth anything with nothing to compare it to. I know JW built at least one twin of my engine, not sure if it had the 4-7 swap. Maybe Jim could shed a little light on it.
    B-rock likes this.
  7. telriv

    telriv Well-Known Member

    If you figure out the firing order ALL "NailHeads" had the 4-7 swap.
  8. alvareracing

    alvareracing Well-Known Member

    per my machinist Robert Fulco who has been racing for a very long time and has done many swaps since the 70's he says, it was originally done looking for more power. But he never really saw anymore power, but he did discover on the dyno that it did smooth the engine out all around. I too, have the swap in my current motor and I have notice mostly on the sound difference and the smooth rev ability it has. maybe is just me with a new toy. It doesn't sound like my other 455's!
    B-rock likes this.
  9. TABuickMike

    TABuickMike Michael Tomaszewski Jr

    The driving point behind the 4-7 swap was to smooth out crankshaft harmonics and "reduce stress" on the crank by improving the firing order. 4-7 is the most popular because it "would have the most impact" of the firing order swaps (2-3 being the other one). I've never heard of any evidence that it actually makes more power, just that the engine can run a little smoother.
  10. 1972Mach1

    1972Mach1 Just some M.M.O.G. guy.....

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